The sigma receptor/binding site (SRBS) is important in the mediation of the effects of other drugs of abuse, such as phencyclidine (PCP), may in part involve the SRBS, although other neurotransmitter receptor systems are equally important. The ascending dopamine systems, which are classically believed to mediate the "rewarding" actions of drug abuse, appear to interact functionally with the SRBS. In extensive preliminary work, we have purified the SRBS approximately 6,000-fold from both rat and bovine cerebellim using an affinity matrix derived from an analogue of 3-PPP, a potent ligand for the SRBS. We determined that this material has pharmacology commensurate with its identification as the SRBS subtype labeled with [3H]-azido-di-o-tolylguanidine, a selective ligand for the DIG subtype of the SRBS) of the affinity purified SRBS, we propose (I) to complete large-scale purification of the SRBS using affinity chromatography; (II) to initiate collaborative studies designed to isolate and clone the SRBS gene; and (III) to further characterize pharmacologically the relationship between the SRBS subtypes labeled by [3H]-haloperidol and [3H]-DTG. The goal of the proposed research is the determination of the primary sequence and molecular structure of the SRBS. The relationship of the putative SRBS subtypes will be clarified through pharmacological studies of the affinity-purified SRBS and the expressed SRBS gene product using a variety of radioligands.